The prize could be thousands of traditionally elusive voters in hard-fought Ohio who would have the chance to register and vote on the same day — if the courts don't intervene.

One-stop voting, scheduled for Tuesday through Oct. 6, would be especially convenient for those Democratic-leaning voters who have traditionally had trouble getting to the polls. It's a reality not lost on two parties locked in a tight race four years after President Bush's 118,000-vote victory in Ohio gave him a second term.

"The populations that we focus on, the lower income and minority populations, move more often," said Teresa James, an attorney working in northeast Ohio for Project Vote, which pushes for greater voting participation. "They're also more likely to have jobs that aren't flexible in terms of voting."

Early voting underwayOhio is one of more than 30 states that allow voters to cast an early ballot. Eight states allow voters to register and vote on Election Day, Nov. 4, while North Carolina allows the practice during early voting.

Turnout has been 10 percent to 17 percent higher than the national average in the six states that had same-day registration and voting before 2006, as well as in North Dakota (which doesn't have voter registration), according to the National Conference of State Legislatures.

Ohio's early voting period has sparked several lawsuits, including one by two GOP-backed voters who say the six-day period in which voters can register and vote on the same day is illegal. That lawsuit is before the Republican-dominated Ohio Supreme Court, which is expected to rule Monday.

Republican John McCain's campaign didn't directly address whether it had plans to take advantage of the early voting window.

"We have a comprehensive grassroots program designed to turn out McCain-Palin supporters once early voting begins," said spokesman Paul Lindsay.

Obama's campaign plans to send staffers to Ohio State University, with about 53,000 students, to encourage early voting among the sometimes hard-to-engage young. Polls show Obama easily carrying the demographic against McCain.

Rallies scheduled for MondayObama's campaign plans to arrange concerts with John Legend, who will hold early voting rallies on Monday in Columbus, Springfield, Dayton and Cincinnati. For campuses far from election boards, Obama aides are organizing car pools to make sure students get to the polls.

On Saturday, Obama's campaign targeted the 100,000-strong college football crowd at Ohio Stadium with a flyover advertising early voting and visits from staffers to surrounding bars.

The Northeast Ohio Coalition for the Homeless believes it can round up 2,000 people from homeless shelters in the Cleveland area and get them to polling places. A donated van will shuttle voters from two shelters, including the city's largest downtown. Seventeen other shelters are providing their own transportation.

Project Vote will go door to door in minority neighborhoods and use vans to transport people to election sites in Cleveland, Cincinnati, Columbus, Dayton and Toledo.

Ohio's Republican-controlled legislature passed a bill in 2005 that enabled all registered voters to vote absentee without providing a reason, beginning Tuesday. The deadline for registering isn't until Oct. 6, so Democratic Secretary of State Jennifer Brunner ruled there is a six-day window in which voters can register and vote at the same time.

Spreading the wordThe GOP maintains that a person must be registered for 30 days to get an absentee ballot. They said Brunner has read a partisan interpretation into law that would give election officials no opportunity to check the validity of voters' registrations.

Amid the legal wrangling, preparations for the window continue.

The progressive Rock the Vote will have a bus tour through Columbus, Dayton, Wilberforce, Athens, Cleveland and Bowling Green — all metro areas or college towns — to emphasize the convenience of the calendar overlap.

Cleveland City Councilwoman Stephanie Howse said activists and Obama volunteers are spreading the word in her ward.

"It's just one piece of our much larger approach to early voting to turn out as many people as possible to get those votes in the bank," Obama spokesman Isaac Baker said.

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.